The present application relates to semiconductor processing, and more particularly to a method of forming a patterned photoresist that has been chemically altered such that it is no longer soluble in its original casting solution.
Directed self-assembly (DSA) refers to the integration of block copolymer (BCP) materials that undergo phase separation with traditional semiconductor manufacturing processes. With DSA, nanoscale dimensions are achieved at a drastically reduced cost by novel material designs without additional equipment upgrades.
Photoresist hardening is commonly used and, in some cases, is a crucial step in DSA processes. Ultra-violet (UV) and thermal frozen approaches can be used to achieve hardening of the photoresist material. These prior art resist hardening processes have some drawbacks associated therewith. For example, in some DSA processes there is a need for the resist to be soluble to the developer after hardening. However, thermally frozen resists are normally not solution soluble after hardening. UV irradiation requires expensive hardware, e.g., the scanner, or additional specifically designed modules or stand-alone tools.
In view of the above, there is a need for providing an alternative method for hardening a photoresist material that can render the harden resist material soluble to the developers after hardening and which does not require expensive hardware, additional specifically designed modules or stand-alone tools.